Certain medical conditions require patients to self-administer medicament(s) over a long period of time, perhaps years. Where possible such medicaments will be formulated for oral delivery which helps with patient compliance. Due to the nature of the medicament (e.g. insulin) oral delivery is not always possible and other administration routes are necessary. Self administration by injection for chronic conditions such as diabetes is therefore relatively common.
Common to most injection devices is the need to use a replaceable dispense interface prior to injection of a medicament. Typically, a disposable needle located within a needle hub is replaced and discarded with every injection. Unfortunately, users of such medical devices may lack manual dexterity, have visual impairment and/or suffer weakness in the hands such that replacing the dispense interface is often difficult.
Furthermore, some injection devices allow the injection of multiple medicaments, either sequentially or simultaneously. Such devices often require a further dispense interface or hub to bring the cartridges containing the medicament(s) into fluid communication with a common outlet. Unlike a conventional needle hub, a dispense interface for a multiple medicament device does not allow a simple screwthread connection between the device and the dispense interface. As the dispense interface must align and fluidly engage with two medicament cartridges the dispense interface must generally be connected in an axial manner.
The drug delivery device may have a single dispense interface. This interface may be configured for fluid communication with the reservoir in the case of a single medicament device or, in the case of a combination therapy device, a primary reservoir and with a secondary reservoir of medicament containing at least one drug agent. The drug dispense interface can be a type of outlet that allows the two or more medicaments to exit the system and be delivered to the patient.
An example of such a device is shown in granted U.S. Pat. No. 5,271,527 in the name of Habley. The Habley device shows a pharmaceutical dispenser for dispensing two or more medicaments from respective medicament cartridges. Attached to said device is a manifold that may be removed by pressing and holding manifold release buttons located on either side of the manifold to overcome the frictional fit and remove the manifold. Such a co-ordinated manoeuvre is difficult to people of reduced manual dexterity and increases the risk of safety issues, such as needle stick injuries. Furthermore, such a removal mechanism provides uncertainty for both the device and the user during the attachment and disconnection procedure as to whether and when the manifold and the medicament in the device are in fluid communication. A partially connected or disconnected cartridge may be in fluid engagement with the device leading to potential loss of medicament or in some cases incorrect dosing.
An object of the present invention is therefore to provide a reliable, safe mechanism for removing a dispense interface from a medicament delivery device.